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53 lines
1.5 KiB
Go
53 lines
1.5 KiB
Go
// +build linux darwin freebsd solaris
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/*
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Copyright The containerd Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package continuity
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import (
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"fmt"
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"os"
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"syscall"
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)
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// hardlinkKey provides a tuple-key for managing hardlinks. This is system-
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// specific.
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type hardlinkKey struct {
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dev uint64
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inode uint64
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}
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// newHardlinkKey returns a hardlink key for the provided file info. If the
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// resource does not represent a possible hardlink, errNotAHardLink will be
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// returned.
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func newHardlinkKey(fi os.FileInfo) (hardlinkKey, error) {
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sys, ok := fi.Sys().(*syscall.Stat_t)
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if !ok {
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return hardlinkKey{}, fmt.Errorf("cannot resolve (*syscall.Stat_t) from os.FileInfo")
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}
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if sys.Nlink < 2 {
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// NOTE(stevvooe): This is not always true for all filesystems. We
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// should somehow detect this and provided a slow "polyfill" that
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// leverages os.SameFile if we detect a filesystem where link counts
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// is not really supported.
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return hardlinkKey{}, errNotAHardLink
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}
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return hardlinkKey{dev: uint64(sys.Dev), inode: uint64(sys.Ino)}, nil
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}
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